Source : Webster's Revised Unabridged Dictionary (1913)

Ballooning \Bal*loon"ing\, n.
   1. The art or practice of managing balloons or voyaging in
      them.

   2. (Stock Exchange) The process of temporarily raising the
      value of a stock, as by fictitious sales. [U.S.]

Source : WordNet®

ballooning
     n : flying in a balloon